Acidolysis of methylal with carboxylic acid anhydroides



United States Patent 2,696,341 Patented Dec. 28, 1954 ACIDDLYSIS OF METHYLAL WITH CARB'OXYLIC ACID ANHYDRIDES No Drawing. Application August 17, 1951, Serial No. 242,439

4 Claims. or. 260-496) This invention relates to the acidolysis of methylal, and more particularly to the preparation of methoxy methyl esters of lower aliphatic acids.

We have discovered that methylal may be reacted, under anhydrous conditions and in the presence of an acid catalyst, with lower aliphatic acid anhydrides to give good yields of a mixture of methyl esters and methoxymethyl esters, which can easily be separated by fractional distillation into pure compounds. The reaction is carried out at reflux temperatures for a period of time sufficient to permit the reaction to go to completion. Ordinarily, six hours of refluxing is sufficient to give good yields of the desired esters, but heating may be continued for longer periods without deleterious effects. It is important, however, that no water be present during the reaction, since, in the presence of water, the methylal will be hydrolyzed to methanol and formaldehyde, reducing the ester yield. The methoxymethyl esters produced in our new process are excellent solvents for cellulose acetate, and show promise as plasticizers and as intermediates for other organic syntheses.

In order that those skilled in the art may more fully appreciate our invention and the method of carrying it out, the following examples are given.

Example I (CI-I30 2CH2+ (CH3CO 20-) CH3COOCH3+CH3COOCH2OCH3 The fact that the 117-118 cut was methoxymethyl acetate is confirmed by the following physical data found as compared with the literature values for this compound.

Found Literature Boiling Point, C 117-118 117-118 Mol. Wt; 102. 4 104 n25/D 1.3917 1. 3980 D20/4 1. 018 0.989 M01. Refraetivity 23. 21 23. 97

Example 11 The procedure of Example I was followed, substituting 1 gram molecular weight of propionic anhydride for the acetic anhydride of Example I. A cut boiling between 130 and 133 C. was collected on fractionation. This out had a strong odor of propionic acid, so it was washed with a 10% sodium bicarbonate solution followed by several water washes. The crude product was dried over magnesium sulfate, and refractionated, a cut boiling at 133 C. being collected, which amounted to a 65% yield of methoxymethyl propionate based on the propionic 5 anhydride used. 31% of the starting propionic anhydride was recovered from a cut boiling between 167 and 169 C. Physical data for the 133 out were determined and compared with the literature values for methoxymethyl propionate as follows:

Found Literature Example 111 lows Found Literature The yield of methoxymethyl butyrate was 62% based on n-butyric anhydride. 27.6% of the starting n-butyric anhydride was recovered unreacted as a cut boiling at 190 to 192 C.

All the esters produced by the synthesis described above are mobile, pleasant smelling liquids which are substantially insoluble in water. They are all excellent solvents for cellulose acetate and should find ready acceptance as solvents and plasticizers.

Having now described our invention, what is claimed is:

1. The process of synthesizing methoxymethyl esters comprising reacting methylal and an aliphatic acid anhydride under substantially anhydrous conditions and at reflux temperatures in the presence of a trace of acid catalyst, and recovering a methoxymethyl ester from the reaction products.

2. The process according to claim 1 in which the acid anhydride is acetic anhydride, and the ester is methoxymethyl acetate.

3. The process according to claim 1 in which the acid anhydride is propionic anhydride, and the ester is methoxymethyl propionate.

4. The process according to claim 1 in which the acid anhydride is n-butyric anhydride, and the ester is methoxymethyl butyrate.

References Cited in the file of this patent UNITED STATES PATENTS Name Date Senkus Feb. 18, 1947 Lippincott July 8, 1947 OTHER REFERENCES Claisen: Berichte 31, 1018.

Post et al.: I. Organic Chem, vol. 2, pages 260-266 (1937).

Fieser et al.: Organic Chemistry" (D. C. Health and (30., Boston, 1944), page 221. 

1. THE PROCESS OF SYNTHESIZING METHOXYMETHYL ESTERS COMPRISING REACTING METHYLAL AND ANALIPHATIC ACID ANHYDRIDE UNDER SUBSTANTIALLY ANHYDROUS CONDITIONS AND AT REFLUX TEMPERATURES IN THE PRESENCE OF A TRACE OF ACID CATALYST, AND RECOVERING A METHOXYMETHYL ESTER FROM THE REACTION PRODUCTS. 